Lymphocytes from both normal volunteers and cancer patients are cryopreserved and stored for varying lengths of time. These are recovered and used in assays of cellular immune functions, and compared to those same assays that are done on fresh cells. These assays are also done in longitudinal fashion on patients undergoing multimodality treatment of cancer. Assays of mitogen stimulation, mixed lymphocyte response, and subpopulation percentages are similar using both fresh and cryopreserved cells. Current methods of cryopreservation may alter the functional response of cells obtained from cancer patients receiving combined modality therapy. This is being evaluated and alternate techniques explored. Parathyroid tissue has been frozen and stored for one to 9 months and reimplanted in parathyroidectomized autologous animals. These endocrine tissues have been able to sustain life, serum calcium levels, and produce parathormone after reimplantation. Serum calcium levels have been evaluated with respect to rate of successful implantation. Pancreatic islet cells are harvested from inbred strains of rats, cryopreserved and stored, and reimplanted into streptozotocin-induced diabetic syngeneic rats. The function of these cryopreserved islets has been successful only in an occasional experiment to date. BIBLIOGRAPHIC REFERENCES: Sears, H.F., and Rosenberg, S.A.: Advantages of using cryopreserved lymphocytes for the sequential evaluation of human immune competence. I. Mitogen stimulation. J. Nat. Cancer Inst. 58: 183, 1977. Sears, H.F., and Rosenberg, S.A.: Increased reliability of cellular immune assays in humans by the use of cryopreserved lymphocytes. Surg. Forum 17: 162, 1977.